The two publications you quote, Impact Erebus. by Gordon Vette, and Verdict on Erebus by Peter Mahon could hardly be called impartial accounts of such an event.
The Foreword to Vette's book is by Peter Mahon, and of course Mahons book is to try and justify his opinions.
You will note that I suggested John King's publication as an unbiased resume from many different sources, including opinion of American judge who differed completely from those published in the books you give as unbiased accounts of the event.